Electric-elevator controller.



No. 679,760. Patented Au 6, mm.

N. 0. LINDSTROM. ELECTRIC ELEVATOR GONTBOLLEB.

(Application filed Apr. X5, 1901.)

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NITED rains ATENT rrrcnt NILS O. LINDSTROM, OF NEW YORK, N. Y., ASSIGNOR TO ALONZO B. SEE AND IVALTER L. TYLER, OF SAME PLACE.

ELECTR'lC-ELEVATOR CONTROLLER.

SPECIFICATION forming part of Letters Patent No. 679,760, dated August 6, 1901.

Application filed April 15, 1901. Serial No. 55,816. (No model.)

To CLZZiUI'I/OHL it may concern.-

Be it known that I, NILS 0. LINDSTROM, a citizen of the United States, residing at the city of New York, in the borough of Queens and State of New York, have invented certain new and useful Improvements in vElectric- Elevator Controllers, of which the following is a full, clear, and exact description.

This invention is an apparatus adapted especially for electric elevators, and is designed to quickly overcome the momentum of the actuating-machine after the main circuit has been opened to stop the car. It is obvious that in cars traveling downward the [5 tendency of the actuating-machine to run after the circuit is opened to stop the car is greater than it is when the car is traveling upward, because in the former case gravity helps to keep the machine in motion, whereas in the latter case gravity acts against the machine and helps to stop it. In overcounterweighted elevators it is difficult, if not impossible, to ascertain whether the car with a given load in traveling up or down will aid the actuating-machine in overcoming its momentum or will tend to increase the momentum, because it is not known whether the actuating-machine is lifting the car or the counterweight. For instance, when the car is coming down with no load it is lifting the counterweight, so that in stopping gravity acting upon the counterweight would aid the actuating-machine in overcoming its momentum. On the other hand, if the car were de- 3 5 scending with a heavy load gravity would increase the momentum of the machine. Hence it is desirable to provide an automatic device which will act properly under all conditions to overcome the inertia of the machine. Such a device must not stop the car too suddenly when gravity is promoting the stop and not too slowly when gravity is tending to retard the stop.

In accordance with my invention I provide a circuit across the brushes of the actuatingmachine which is closed automatically when the main circuit of the actuating-machine is opened to stop the car. This circuit contains a resistance and a solenoid in series, the latter adapted to cut out the resistance when the flow of current in the circuit is sufficiently great. When the main circuit is opened under conditions which would tend to keep the actuating-machine running, as when gravity is promoting. momentum, thecurrent generated in the-circuit is so great as to cause the solenoid to cut out the resistance at once, whereupon the heavy current then flowing will quickly consume the momentum of the machine and the elevator-car will be stopped 6c within a predetermined short time. On the other hand, when the main circuit is opened under conditions which would tend to overcome the momentum of the machine, as when gravity is against the momentum, the current generated in the circuit is not sufficient to cause the solenoid to cut out all, if any, of the resistance, and the momentum is overcome largely by the prevailing mechanical conditions, which bring the car to a stop in substantially the same time as under the previously-described electrical conditions. I provide for the gradual cutting out of the resistance in order to avoid too-sudden stops,

and this is further promoted by the use of an air-cushion, which retards the final movement of the device which cuts out the resistance.

In the accompanying drawings, Figure 1 is a conventionalrepresentation of the apparatus constituting the features of my inven tion. Fig. 2 is a similar view of the same apparatus applied to an elevator.

A is an elevator-car, and B is a counterweight therefor, connected -by means of a cord a, passing over a driving-drum b.

O is an electric actuating-machine geared to the drum 6 and whose main circuit is indicated by the wires 1 and 2, containing the terminals 3 and 4t.

5 and 6 are the wires of a short circuit across the brushes of the machine 0, said wires containing the terminals 7 and 8, which are adapted to be bridged immediately after the terminals 3 and 4 are disconnected. A switch-arm for accomplishing this is indicated at e and may be moved by means of the pilot-rope e, passing over the pulley (2 or in any other desired way. The circuit 5 6 includes a solenoid S and a resistance R. The resistance is divided into sections ter- I00 minating in the two rows of contactsr and r in a Well-known manner. The core .5 of the solenoid carries a cross-head s, insulated by a sleeve .9 and bearing at each end against the rows of contacts 4' and 0', respectively, thus forming an electric contact between the two rows. f is a bearing to guide the corein its movements. The axial chamber in the solenoid is closed across the end by a plate o, so that the movement of the core into the chamber will compress the air therein and be retarded. Sufficient clearance is allowed, however, between the core and the walls of the chamber to permit the air to finally escape, and thus allow the core to eventually complete its stroke.

The operation is as follows: The car in traveling up and down in the shaft is in stopping, as before explained, likely to aid the actuating-machine in coming to a stop or to retard the stop; but in all cases when the main circuit of the machine 0 is opened to stop the car the circuit 5 6 across its brushes is closed. If the conditions in any instance are such that gravity promotes the momentum of the machine and would therefore tend to make a slow stop, a heavy current is generated in the circuit 5 6, which energizes the solenoid s, causing it to cut out the resistance R, thus putting the machine upon a practically dead short circuit, which rapidly strengthens its field-magnet and consumes the momentum. This, however, is not so suddenly accomplished as to produce a jar upon the car and passengers, because the entire resistance is not at once cut out owing to the retarding influence of the air-cushion. The time element can be accurately determined by the construction of the resistance, the magnet, and the air-cushion. On the other hand, if the conditions are such when the machine is to be stopped that gravity is acting against the momentum of the machine and is therefore helping the machine come to a stop, the current generated in the circuit 5 6 is not excessive and the magnet S is not sufficiently energized to cut out more than a very small portion of the resistance. The result is that the field-magnet of the machine does not build up so rapidly and the momentum is chiefly overcome by the prevailing mechanical conditions,and the machine stops in about the same time as before. It will be seen, therefore, that the apparatus automatically stops the machine without jarring the car in about the same time, regardless of the conditions under which the car is running.

Having described my invention, I claim- 1. In an electrically-actuated elevator, the combination of the car,the actuating-machine and its main circuit, a circuit across the brushes of the machine, and means for closing the latter circuit each time the main circuit is opened.

2. In an electrically-actuated elevator, the combination of the car, the actuating-machine and its main circuit, a circuit across the brushes of the machine, means for closing the latter circuit each time the main circuit is opened, a resistance in said circuit across the brushes, and means for automatically cutting' said resistance out, for the purpose set forth.

3. In an electrically-actuated elevator, the combination of the car, the actuating-machine and its main circuit, a circuit across the brushes of the machine, means for closing the latter circuit each time the main circuit is opened, a resistance and an electromagnet in said circuit across the brushes, said electromagnet being adapted to cut the resistance out upon an excessive flow of current.

In Witness whereof I subscribe my signature in presence of two witnesses.

NILS O. LINDSTROM.

\Vitnesses:

WALDo M. OHAPIN, FRANK S. OBER. 

